Lightweight thin flexible polymer coated glove and a method therefor

ABSTRACT

A lightweight thin flexible latex glove article having a polymeric latex coating that penetrates the front portion of a knitted liner half way or more through the liner thickness and for at least a portion of the knitted liner, not penetrating the entire thickness. For example, the liner can be knitted using an 18-gauge needle with 70 to 221 denier nylon 66 multi-filament yarn. The polymer latex coating can be 0.75 to 1.25 times the thickness of the knitted liner. Over 30% reduction of glove thickness is achieved resulting in three times greater flexibility. The polymer latex coating may be foamed with 5 to 50 vol % air content. Open celled foamed latex coating may be coated with a dispersion of fluorochemical dispersion to prevent liquid permeation into the glove. The process can include steps to gel the latex emulsion at interstices of the yarn to prevent further penetration of the emulsion into the liner.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C. § 119(e)to U.S. Provisional Application No. 60/775,948, filed Feb. 23, 2006, thedisclosure of which is hereby incorporated by reference in its entirety.

FIELD

Aspects of the invention relate to a lightweight thin flexible latexarticle having a thin knitted liner partially covered and penetrated bya thin porous or continuous latex layer thereby providing enhancedflexibility. The porous latex layer can be treated to providebreathability without water or oil permeability.

BACKGROUND

Gloves are commonly used to protect hands in an industrial or householdenvironment. The gloves, upon wearing, fill with sweat and feel clammyto the user. Advances in glove manufacturing technologies have resultedin partial coating of a fabric knitted liner with an adherent latexlayer so that glove is breathable in the exposed knitted areas. Theknitted liners are fabricated from relatively thick robust yarns with a319 denier, (a denier defined as number of grams of a 9000 meter yarn)or greater using 15-gauge knitting needles or larger. The latex layerformed is also correspondingly thick resulting in a glove with a heavyfeel that has limited flexibility. When the latex layer used is madeporous in order to provide breathability, the resulting thickness of theporous latex layer is generally greater resulting in an awkward feelingglove with limited touch sensitivity. For equivalent wear resistance,the foam layer must be thicker than a non-foamed layer. A number ofpatents address gloves and their forming methods using relatively thickknitted liner and a thick coating of latex layers. The combination of athick knitted liner and a thick foamed latex layer do not result in asmall overall glove thickness and the glove product does not provideflexibility and easy mobility of fingers and hand.

U.S. Pat. Nos. 4,514,460 and 4,515,851 to Johnson disclose slipresistant surfaces. U.S. Pat. Nos. 4,555,813 and 4,567,612 to Johnsondiscloses slip resistant gloves. U.S. Pat. Nos. 4,569,707 and 4,589,940to Johnson disclose methods of making foamed slip resistant surfaces.This porous surface is particularly useful for workers in workenvironments wherein the gloves are breathable and havemoisture-absorbing properties. The surface is a foam surface laminatedto a knitted or woven web substrate. The polyurethane, polyvinylchloride, acrylonitrile; natural rubber, synthetic rubber foam, prior tolamination, may be foamed with varying amounts of air depending upon thedegree of abrasion resistance required. The foaming may be by mechanicalor chemical means.

U.S. Pat. Nos. 4,497,072 and 4,785,479 to Watanabe disclose porouscoated glove and method of making a glove. Broken air bubbles form theporous surface. The air cells are closed and provide cold protection andwaterproof qualities. The thick closed cell foam is bonded to woven orknitted sewn fabric. Due to its cold protection properties this is athick glove with minimal flexibility.

U.S. Pat. No. 5,322,729 to Heeter et al. discloses method and apparatusfor producing a breathable coated fabric. The method involves coating afabric substrate with a resin then opening pores in the resin bydirecting a flow of air through the fabric substrate and resin coating.The pores provide breathability of the coated fabric and allow for avapor or moisture transmission rate about ten times that of a resincoated fabric without pores. Forcing air through uncured resin generallyresults in uncontrolled airflow passages and in the worst case,delamination of the resin from the fabric.

U.S. Pat. No. 5,581,812 to Krocheski discloses a leak proof textileglove. A cotton glove is inverted and dipped in a PVC or polyurethanelatex solution to make the cotton glove impervious to water or oil. Theglove is inverted so that the cotton surface is the gripping surfacewhile the latex layer contacts the skin. The latex layer may beoptionally flocked to provide a better skin feel. There is no knittedliner in this glove. The latex layer applied is impervious to water oroil, but is not breathable.

U.S. Pat. No. 6,527,990 to Yamashita et al. discloses a method forproducing a rubber glove. The rubber glove is made by sequentialimmersion of a glove mold in coagulating synthetic rubber latex thatcontains thermally expansible microcapsules. During the vulcanization ofthe synthetic rubber latex, these microcapsules burst providingexcellent anti-blocking and grip under wet or dry conditions. There isno knitted liner in this glove and the latex layer completely surroundsthe hand.

U.S. Patent Publication 2002/0076503 to Borreani discloses a clothingarticle such as a working or protective glove made from textile support.The textile support receives an adherence primer in the form of anaqueous calcium nitrate. The textile support with the adherence primeris coated with a foamed aqueous polymer, preferably an aliphaticpolyether urethane or polyester urethane entirely or partially. Thefoamed aqueous polymer only appears on the support outer part withoutgoing through the textile support mesh. When the textile support is toohydrophilic, 2-5% fluorocarbon is added to the aqueous latex emulsion.The size of the yarn in the textile support is not indicated. The patentdoes not indicate why the aqueous polymer does not penetrate the textilesupport mesh. The viscosity of the aqueous air foam is in the range of1500 to 3000 centipoise and this thick foam may not enter the mesh, butonly contacts the fibers at very localized regions creating a poor bondbetween the polymeric layer and the textile support.

U.S. Patent Publication 2004/0221364 to Dillard et al. disclosesmethods, apparatus, and articles of manufacture for providing a foamglove. A textile shell is coated with a foamed polymeric coating that issupported in part by the surface of the textile shell. Sufficient amountof air mixed with the base polymer to lower the density of the basepolymer between about 10 to 50% of the original density of the basepolymer. The textile shell is knitted using nylon, polyester, aramid,cotton, wool, rayon or acrylic fibers. The foam cells absorb liquid,which indicates that the foamed polymer does not protect the hand fromwater or oil present on the object being gripped. The yarn is said to beknitted with a 15-gauge needle using a Shima Seki knitting machine thatfixes the size of the knitted textile shell to be a thick shell, not athin shell. As a result, the foam glove is a thick product and is notvery flexible.

GB 730879 discloses laminated material and method of making same. Thelaminated material comprises a backing layer and a foam latex layersecured together by penetration substantially half way through thebacking layer fabric, the exposed surface of the latex layer having hadremoved by friction that outer portion which can be readily separatedthere from. The penetrated foam does not separate by friction. This isnot a foam layer on a backing layer that remains intact during use.

GB 2400051 and WO2005088005 disclose a polymeric garment material. Thepolymeric garment material is made by applying coagulant to a substrate,which may be present on a mould, applying foam of a polymeric materialto the substrate, allowing the coagulant to coagulate some of the foamand removing uncoagulated foam from the substrate to leave a layer ofcoagulated polymeric material on the substrate. Spraying liquid such aswater or directing a jet of gas such as air onto the substrate mayremove the uncoagulated foam. After removing uncoagulated foam, thesubstrate may be immersed in water to remove coagulant. The polymericmaterial may be one or more of nitrile latex, natural latex,polyurethane latex, polyvinyl chloride latex, neoprene andpolyvinylacetate. Blasting the foam leaves only a portion of the appliedfoam layer providing non-uniform coverage of the foamed elastomericlayer. The pressure of the jet may force the uncured gelled polymer intothe interstices between the fibers of the substrate.

Accordingly, there is a need in the art for thin lightweight highlyflexible latex gloves that has the latex layer applied to only portionsof the lightweight knitted liner providing breathability of the glove.It is also desirable to have a latex layer that is porous providingadditional breathability and improved flexibility. It is desirable toprevent entry of oil or water through the porous latex layer.

SUMMARY

The flexibility of a glove is a strong function of the thickness of theglove and increases according to the inverse of the cube of thethickness. Thus a reduction of the thickness of an elastic body such asa latex layer coated glove by 30 percent increases the flexibility by afactor of three. The thickness of the glove is made up of the thicknessof the knitted liner and the thickness of the adherently bondedpolymeric layer. The flexibility may be greater than that expected basedon elastic body calculation since the knitted liner is capable ofdisplacing at the knitted yarn level. This factor is even moresignificant when the individual yarn is made up of a plurality ofstrands instead of being a monofilament yarn. This enhancement inflexibility is lost, if the polymer completely penetrates the liner; thestiffness of the glove drastically increases due to the stiffening ofthe knitted layer.

Typically, for coated knitted work gloves, a commonly used knittingneedle is a 15-gauge needle. Shima Seiki manufactures knitting machinesthat are capable of using finer knitting machine needle size, such as an18-gauge needle. According to Spencer D. J. Knitting Technology, p 209,1993, the gauge of the knitting machine needle has a definiterelationship with the denier of the yarn that can be used. For example,a needle of gauge 15 uses 319 denier yarn. However, a needle of gauge 18uses 221 denier yarn. Denier is defined as number of grams of a yarnhaving a length of 9000 meters. Therefore, a liner knitted by an18-gauge needle is approximately 30% lighter than a liner knitted with a15-gauge needle. The small diameter of 221 denier yarn knitted with an18-gauge needle also has higher packing density per square unit area,thereby presenting a smoother surface for latex dip resulting in asmoother, smaller thickness of latex.

Since the yarn size of an 18-gauge needle yarn is smaller than that of a15-gauge yarn, the 18-gauge thin knitted liner has smaller spacesbetween the stitches and/or yarns. Use of this 18-gauge knitting needlegenerally means that the stitches and /or yarns in the knitted liner arespaced one to three times the yarn diameter. As such, small intersticesare provided between the yarns and/or stitches. In order to bond a latexlayer to the thin knitted liner the latex should penetrate half way ormore through the thickness of the thin knitted liner. A penetration ofthe latex layer less than half the thickness generally results in pooradhesion, and can result in unexpected separation of the latex layer.However, if the entire latex layer penetrates the knitted linercompletely, the polymeric coating is available for contacting the skinof the glove wearer resulting in undesirable effects and sometimesirritation. This problem can be, and has been previously, managed usinga 15-gauge needle yarn due to the large thickness of the lineravailable. This balance between adhesion of the latex layer andprevention of skin contact of the penetrated latex has not been solvedfor 18-gauge needle yarn, particularly when using an aqueous latexemulsion.

Generally stated, an aspect of the present invention provides a glovewith a thin knitted liner and a polymeric latex coating layer which isapproximately 0.75 to 1.25 times the thickness of the knitted layer,whereby the polymeric latex coating penetrates half way or more throughthe thickness, and for at least a portion of the knitted liner, thepolymeric latex coating does not penetrate the entire thickness of thethin knitted liner. Yam size is 221 denier or less. In one embodiment,an 18-gauge needle is used to knit the liner. In another embodiment, askin-contacting surface of the knitted liner is substantially free ofthe polymeric latex coating. By reference to being substantially free ofthe polymeric latex coating, it is meant that more than a majority thesurface area of the skin-contacting surface of the knitted liner has nolatex coating. In one embodiment, the skin-contacting surface of theknitted liner is approximately 75% or more free of the polymeric latexcoating. In one embodiment, the yarn used is partially oriented nylon66, with a specification 2-ply/70 denier/103 filament or 2 ends of1-ply/70 denier/103 filament, each filament having 0.68 denier,typically a filament with a denier that is less than 1 denier perfilament. This bundle of multi-filament yarn with a large number of verysmall denier filaments is very highly flexible and therefore, theknitted liner is also very highly flexible. The 18-gauge needle can takea single yarn of 2 ply of 70 denier yarn or 1 ply yarn of 140 denieryarn or a yarn as large as 221 denier to knit the liner. The polymericlatex layer is only coated over selected portions of the glove generallyincluding the palm and finger regions of the glove while the portion ofthe liner at the back of the hand are not coated with the polymericlatex layer. In detailed embodiments, the polymeric latex coating isselected from a group consisting of natural rubber, syntheticpolyisoprene, styrene-butadiene, carboxylated or non-carboxylatedacrylonitrile-butadiene, polychloroprene, polyacrylic, butyl rubber, orwater-based polyurethane (polyester based or polyether based), orcombinations thereof. In a specific embodiment, the polymer comprisescarboxylated acrylonitrile-butadiene latex formed from an aqueous latexemulsion. In an embodiment, the overall thickness of the glove is in therange of 0.6 mm to 1.14 mm. In a detailed embodiment, the overallthickness is from approximately 0.70 to approximately 0.90 mm.

In a second embodiment, the polymeric latex layer is foamed using welldispersed air cells in the range of 5 to 50 volumetric percentageforming closed cells or open cells with interconnected porosity in thepolymeric latex layer. Closed cells provide a liquid proof polymericlatex coating that is highly flexible, soft and spongy, and providesgood dry and wet grip. Closed cells are normally associated with aircontent in the 5 to 15 volumetric percent range. Open cells that areinterconnected normally occur in the 15-50% air volumetric range andprovide breathability of the glove through the foamed polymeric latexlayer. The glove with open cell foam exhibits breathability in the sensethat one can blow air through the polymeric latex coating of the gloveby cupping the mouth, encountering very little resistance. Breathabilityof the glove is always available through portions of the knitted linerthat is not coated with the foamed polymeric latex layer, such as thebackside of the glove. This foamed polymeric latex layer also penetrateshalf or more of the thickness of the knitted liner, and for at least aportion of the knitted liner, the polymeric latex layer does notpenetrate the entire thickness, thereby substantially avoiding skincontact of the polymeric latex.

In a third embodiment, the external surface of the unfoamed or foamedpolymeric latex layer is coated with an aqueous fluorochemicaldispersion coating immediately after aqueous latex dip prior to curing,approximately 0.5 to 2 microns thick that cures together with the latexlayer during vulcanization heat treatment, changing the contact angle ofany liquid such as water or oil preventing their entry through the finedimensioned pores of the foamed polymeric latex layer or anyimperfections in the unfoamed latex layer. Thus, breathability of thefoamed polymeric latex layer is preserved without the penetration of oilor water from entering the interior of the glove.

In a fourth embodiment, the polymeric latex layer is provided with aplurality of cavities so that the external latex surface of a glove hassuperior gripping properties of wet, oily, and/or dry surfaces. Theenhanced surface area provided by the cavities provides for surface areafor capturing boundary layer oil or water film from the work surface,which is being gripped. Moreover, application gripping pressuredisplaces the boundary layer of oil or water from the boundary layerover the work article and pushes it into the volume of the cavities.Since the lightweight knitted liner of the present invention isrelatively low in thickness and the corresponding latex layer thicknessis also small, the cavities need to be limited in its penetration depth.The process of creation of cavities that are uniformly distributed overthe latex external surface is disclosed in US Patent Publication No.2005/0035493 to Flather et al., the content of which is herebyincorporated by reference in its entirety.

A method of manufacturing lightweight thin flexible polymer coatedgloves in accordance with one aspect of the present invention comprisesthe steps of 1) dressing a hand shaped ceramic or metallic former withan 18-gauge knitted liner, 2) immersing the former with the knittedliner in a coagulant solution comprising, for example, calcium nitratecoagulating solvent or alcoholic solution or aqueous solution orcombinations thereof, 3) removing the former with coagulant coatedknitted liner, 4) dipping the former with coagulant coated knitted linerinto a tank containing an aqueous polymeric latex emulsion to a precisedepth so that the polymeric latex emulsion penetrates half way or more athickness of the knitted liner and for at least a portion of the knittedliner, the polymeric latex emulsion not penetrating the entire thicknessof the knitted liner; and the coagulant gels the polymeric latexpreventing further penetration of the latex into the thickness of theknitted liner 5) removing the former with knitted liner with polymericlatex coating, 6) washing the former with the gelled polymeric latexcoating, 7) heating to vulcanization temperature for selected timeperiod and 8) additional washing the glove to remove coagulant andoffensive latex proteins and latex stabilization and processingchemicals. The process variables, which control the penetration of thepolymeric latex emulsion include, control of viscosity of the emulsionand control of dip depth in the polymeric latex emulsion tank. Withoutintending to be bound by theory, hydraulic pressure in the tank ofaqueous polymeric latex emulsion also contributes to the depth ofpenetration. After washing according to step 6, the external surface ofthe foamed polymeric latex coating may be coated with an aqueous orsolvent-based aqueous fluorochemical dispersion coating and vulcanizedaccording to steps 7 and 8 to create a hydrophobic and oleophobiccoating preventing entry of oil or water through any imperfection of thelatex layer.

In a second embodiment of the process, the polymeric latex solution ofstep 4 is foamed using air pressure or mechanical agitation. Thepenetration of the foamed polymeric latex emulsion through the entirethickness of the knitted liner, for at least a portion of the knittedliner, is prevented either by control of depth of immersion as detailedin the first embodiment or by blocking as detailed in the thirdembodiment detailed below. The process variables, which control thepenetration of the foamed polymeric latex emulsion, include control ofviscosity of the emulsion and control of dip depth in the polymericlatex emulsion tank. After washing, according to step 6, the externalsurface of the foamed polymeric latex coating may be coated with anaqueous or solvent-based aqueous fluorochemical dispersion coating andvulcanized according to steps 7 and 8 to create a hydrophobic andoleophobic coating. The foam may provide breathability especially whenair content is in the range of 15-50% providing a open celled structure,yet the fluorochemical coating prevents entry of oil or water into theinterior of the glove.

In a third embodiment, the knitted liner is first dressed on a handshaped former. The external surface of the knitted liner is coated witha viscous thick coating of a blocking coating of, for example, highmolecular weight PVA, molten wax, solvent-based polyurethane, orcombinations thereof, or other materials that block the intersticesbetween the yarns of the knitted liner. Advantageously, a suitableblocking compound may be added to the coagulant solution. Optionally,the blocked knitted liner is stripped from the former and is invertedand dressed on a hand shaped ceramic or metallic former. The stepslisted in the first embodiment are carried out except that in step 4, nospecial care is needed to control the depth of immersion of the formerwith the knitted liner since the polymeric latex emulsion cannotpenetrate the full thickness of the knitted liner since the intersticesbetween the yarns are blocked by, for example, PVA, wax, solvent-basedpolyurethane, or the like. During step 6, certain blocking materials,for example, PVA or wax, are removed during the washing step. The PVA,for example, decomposes and the wax, for example, drips away. Because ofthis, portions of the skin-contacting surface of the glove are free ofthe polymeric latex coating, and exposure of a user's skin to thepolymeric latex coating is minimized. Solvent-based polyurethane as ablocking agent is especially useful since it need not be removed fromthe knitted liner since a solvent-based polyurethane coating presents askin friendly surface, unlike polymeric latexes.

In a fourth embodiment of the process, the method of manufactureincludes dipping a coagulant coated knitted liner dressed on a formerfirst in an aqueous latex emulsion to seal off the inter fiber spaces inthe knitted liner and latex penetrating more than half way through theliner, but not penetrating the liner all the way. This thin latex layercoated liner is further dipped in a second latex bath and the knittedliner with the second layer of latex is subjected to a fluidized bedsalt treatment. The salt particles, which are individually separated andkept afloat by the fluidized bed contact the second layer whichimmediately gels the latex replicating the shape of the salt particle.This salt containing second layer that is present over the first latexlater and the knitted liner is subjected to water wash to remove thesalt particles. This washing action does not change the cavity structureproduced in the second latex layer since the second latex layer isalready gelled and has some mechanical integrity. The washed glove isthen subject to vulcanization heat treatment, which cures the first andsecond latex layers and bonds them together.

The features of the lightweight thin flexible polymer coated gloveinclude, singly or in combination, the features set forth below:

First, a lightweight thing flexible liner is prepared from a yarn of 221denier or less. In one embodiment, an 18-gauge needle is be used to knitthe lightweight thin flexible liner.

Second, various yarn configurations can be used to achieve an overalldenier of 221 or less. For example, an 18-gauge needle is capable ofusing 2 twisted strands of 1-ply/70 denier/103 filament nylon 66 yarn(140 denier), or one strand of a 2-ply/70 denier/103 filament nylon 66yarn (140 denier), or one strand of a 221 denier yarn in the thin linerknitting process. Generally, any combination of strands, plys, andstrand deniers can be used to result in a yarn having a denier of 221 orless.

Third, the lightweight thin knitted liner has a weight and thickness ofapproximately 30% less than standard knitted liners using a 15-gaugeneedle. A corresponding latex coated lightweight thin knitted linerglove will likewise be thinner and lighter than a latex-coated knitterliner from a 15-gauge needle.

Fourth, the lightweight thin knitted liner is made of a mesh that isclosely spaced with small interstices. The interstices between the yarnsof the knitted liner are typically from one to three times the diameterof the yarn used, when using a properly sized needle gauge. Thisparameter is easily obtained by proper selection of the yarn andknitting parameters. However, when a knitting needle having an excessivesize is used, the spacing between the yarns in the knitted liner is muchlarger and is generally unsuited for latex dipping since polymeric latexemulsion penetrates the entire thickness of the liner.

Fifth, a coating geometry, in a detailed embodiment, is provided whereinsaid knitted liner is coated with a polymeric latex coating thattypically penetrates halfway or more through the thickness of theknitted liner providing excellent adhesion of said coating to the liner,but the coating preferably does not penetrate the entire thickness ofsaid knitted liner, for at least a portion of the knitted liner, therebysubstantially reducing contact of the coating with a user's skin.

Sixth, the geometry, in another detailed embodiment, is created by aprocess wherein a knitted liner is dressed on a former, dipped in acoagulant and subsequently dipped to a predetermined depth in an aqueouspolymeric latex emulsion tank or the interstices being blocked prior todressing on the former creating gelled regions at the intersticesbetween fibers in the knitted liner substantially preventing furtherpenetration of the emulsion through the thickness of the liner.

Seventh, the geometry, in a specific embodiment, is created by firstblocking the interstices between the yarns in a coagulant coated knittedliner, and then coating opposing surface of the liner with a polymericlatex emulsion to create a polymeric latex coating that penetrates halfway or more through the thickness of the knitted liner, and for at leasta portion of the knitted liner, the polymeric latex does not penetratethe entire thickness of the knitted liner.

Eighth, the gripping surface of the latex layer of the glove is providedwith plurality of cavities providing improved wet, oil surface, dry gripby increasing the friction and removing boundary liquid or oil film fromthe work surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of a knitted liner with the polymericlatex layer penetrating half way or more through the thickness of theknitted liner.

FIG. 2 illustrates a yarn that can be used in accordance with one aspectof the present invention.

FIG. 3 is a photograph of a glove made with a knitting machine using a15-gauge needle representing a prior art knitted liner.

FIG. 4 is a photograph of a glove made with a knitting machine using an18-gauge needle in accordance with one aspect of the present invention.

FIG. 5 is an SEM photomicrograph of the cross-section and upper surfaceof a glove wherein the latex surface is provided with a pluralities ofcavities.

DETAILED DESCRIPTION

The flexibility of an elastic article is strongly determined by thegeometry of the object. An elastic beam having a width ‘B’ with athickness ‘T’ and a length ‘L’ subjected to a central load ‘P’ has amaximum deflection ‘δ’ at the load point given by the equation:

$\delta = \frac{{PL}^{4}}{48\mspace{14mu} {EI}}$

where ‘E’ is the elastic modulus and I is the moment of inertia aboutthe neutral axis given by the equation:

$I = \frac{{BT}^{3}}{12}$

where ‘B’ is the width of the beam and ‘T’ is the thickness of the beam.Similar relationship exists for other loading geometries of ‘P’. In allcases, ‘δ’, the deflection is inversely proportional to the third powerof the thickness ‘T’. Therefore decreasing the thickness of the beam by30 percent results in an increase in deflection or flexibility by afactor of 2.91 or nearly three.

Flexibility of gloves having an elastomeric coating, such as a glovelatex coating, can be increased by decreasing the thickness of theglove. Since the glove has a knitted liner the flexibility may beenhanced by only partially penetrating the knitted liner thereby takingadvantage of the knitted liner due to relative movement between theyarns of the knitted liner and the movement between the filaments of anindividual yarn. This enhanced flexibility requires use of a thinnerknitted liner and applying a thinner polymeric coating. Challenges areencountered in each of these approaches as discussed next.

Conventional knitting machines such as those supplied by Shima Seikitraditionally use a 15-gauge needle for knitting glove liners. Thisneedle can accommodate a total yarn denier of 319 as indicated by p 209of the book Knitting Technology by D. J. Spencer, published in 1993. Adenier is the weight of the yarn in grams for a yarn length of 9000meters. Considering nylon 66, which has a density of 1.13 g/cm³, thevolume of 319 grams is 282 cm³. The average cross-sectional area of the9000 meter yarn, in turn, is 0.031 mm, thereby resulting in a yarnhaving an average yarn diameter of 0.19 mm. This cross-section diametercalculation reflects the result for a single monofilament yarn, but amultifilament yarn of the same denier may have substantially largercross-section diameter since voids are present between multiplefilaments of the yarn. When these yarns are knitted to form a liner, atthe crossing points, the cross-section diameter is nominally 0.38 mm.Since these yarns are normally produced by twisting multiple strands offiner filaments, the yarn diameter may be larger and correspondingly,the knitted liner may be thicker. In addition, the knitting process hasa certain degree of slackness; the thickness of the knitted liner may belarger due to this slackness. For example, two ends of 2 ply/70denier/34 filament with each filament having a denier of 2.08 has atotal nominal denier of 280, which is suited for knitting with a15-gauge needle to produce a prior art standard liner that is dippedwith latex to produce a standard prior art glove. A liner prepared fromsuch a yarn has a measured uncompressed thickness of 1.34 mm and acompressed thickness under 9 oz (225 grams) load of 1.13 mm using anAmes Logic basic thickness gauge model no. BG1110-1-04 according to ASTMD1777. The knitted liner is measured to have a basis weight of 167.9±5.3grams/mm². When the knitted liner is coated with the polymeric latexemulsion, the yarns tend to come together providing a knitted linerthickness approximating the compressed thickness. The thickness of thepolymeric latex coating approximates the thickness of the knitted liner.A 15-gauge knitted liner prepared from two ends of 2 ply/70 denier/34filament coated with a polymeric latex coating results in a glovethickness of 1.15 mm to 1.5 mm such as Ansell 11-800. Ansell 11-600glove which is a 15-gauge knitted glove is coated with solvent-basedpolyurethane with complete penetration and has a thickness nearly equalto that of the knitted liner which is approximately 1 mm. A Showaproduct BO-500 also uses a 15-gauge knitted liner which is completelypenetrated by solvent-based polyurethane has a thickness nearly equal tothat of the knitted liner which is approximately 1 mm.

Shima Seiki also has knitting machines that can use 18-gauge needles.Thus, smaller denier yarns may be used to produce knitted liners.According to p 209 of the book Knitting Technology by D. J. Spencer,published in 1993 the 18-gauge needle can use yarn with a total denierof 221. Considering the density of nylon 66 (1.13 g/cm³), this yarn hasa volume of 195 cm³. The average cross-sectional area of the 9000 meteryarn, in turn, is 0.021 mm², thereby resulting in a yarn having anaverage yarn diameter of 0.16 mm. However, when a 140 denier yarn isused, the cross-sectional area is 0.014 mm² or an average yarn diameteris 0.13 mm. Thus, at yarn cross-over points, when using a 221 denieryarn, the knitted liner will have a minimum thickness of 0.32 mm. Inpractice this thickness is expected to be larger due to use of multiplefilaments. In a specific example, a 70 denier yarn made-up of 103filaments of 0.68 denier can be used. The knitted liner also has acertain degree slackness. In addition to the use of 2 ends of a 1-ply 70denier/103 filament yarn, the process may use a 2-ply/70 denier/103filament yarn with a 140 denier or a 221 denier yarn to knit a liner.The use of a single 2-ply/70 denier/103 filament yarn wherein eachfilament has 0.68 denier resulted in a knitted liner, which is 0.83 mmin the uncompressed state and 0.67 mm in the compressed state under 9 oz(225 grams) load using Ames Basic Logic thickness gauge model no.BG1110-1-04 according to ASTM D1777. This knitted liner is measured tohave a basis weight of 142.9±1.3 grams/m². When this 18-gauge needleknitted liner is coated with polymeric latex coating with a latex layerthickness close to the thickness of the knitted liner, the glove has afinal thickness in the range of 0.6 mm to 1.14 mm. In a detailedembodiment, the glove has a thickness of from approximately 0.70 toapproximately 0.90 mm. Since the yarn is made from very fine diameterpartially oriented fibers, the flexibility of the yarn is very good.Thus the thickness of the glove is reduced by better than 30% providingbetter than 3 times improvement in the flexibility of the glove comparedto a glove having a liner knitted from a 15-gauge needle. The overallweight of the latex glove is, likewise, lighter.

The gauge knitting needle used is generally selected according to thedenier of the yarn being used. However, it is possible to use a largergauge needle for a smaller denier yarn and this combination results inexcessive spacing between the yarns in the knitted liner, which islarger than the desired one to three range. This is illustrated by thevariations in the spacing between yarns in a knitted liner when 15-gaugeand 18-gauge knitting needles are used. The interstices space istypically in the range of one to three times the diameter of the yarnused to knit the liner, when a proper needle gauge is selected. The15-gauge needle can use a 280 denier yarn, having an average yarndiameter of 0.19 mm. The 18-gauge needle can use a 140 denier yarn,having an average yarn diameter of 0.13 mm. The relationship between theyarn diameter and the interstices changes when the liner is put on aformer so that the interstices diameter can be three times larger thanthe yarn diameter.

Technical problems exist when thin knitted liners are coated withaqueous polymeric latex. Difficulties with adhering the latex layer tothe thin knitted liner and irritation to the skin of certain users uponcontact with the latex layer have been recognized. As such, 18-gaugeneedle-knitted liners thus far have not been coated with aqueouspolymeric latex emulsions. To address these technical problems, inaccordance with aspects of the present invention, the reduced thicknessof the knitted liner requires the polymeric latex emulsion to penetrateapproximately half way or more to create adhesion between the polymericlatex coating and the knitted liner. For at least a portion of theknitted liner, the latex layer does not penetrate the entire thicknessof the knitted liner, thereby substantially reducing contact between thepolymeric latex and the user's skin when the glove is worn. The overallmargin of error is significantly reduced with approaches according toaspects of the present invention.

Attempts to produce thinner gloves such as Ansell 11-600 or ShowaBO-500, which use 15-gauge needle knitted liners and have thicknesseswhich are penetrated by solvent-based polyurethane, result in stiffgloves. The liners of these gloves become completely penetrated by thesolvent-based polyurethane, thereby reinforcing the liner and increasingits elastic modulus ‘E’, and thereby decreasing the deflection. Alsochemicals used in the solvent-based polyurethane do not readily wash offresulting in a stiffer glove. Despite this, in certain embodiments ofthe present invention, solvent-based polyurethanes are acceptableblocking agents and can be used along with the polymeric latex coatingswhich penetrate half way or more and for at least a portion of theknitted liner. The gloves of aspects of the present invention accomplishthis glove geometry regardless of the yarn size using, for example, an18-gauge needle.

FIG. 1 illustrates schematically the arrangement of yarns in the knittedliner and its relationship to the polymeric latex coating, which may befoamed or unfoamed. The yarns having an average diameter D are knittedin the liner producing a liner with a thickness T1. The polymeric latexcoating of thickness T2 penetrates the knitted liner producing anoverall glove thickness. For at least a portion of the knitted liner,the distance defined by T-T2 is not penetrated by the polymeric latexcoating and the degree of penetration is defined by the ratio (T-T2)/T1.If the coating penetrates the entire thickness of the liner, theunpenetrated region is zero regardless of the thickness T1 of theknitted liner. The polymeric latex coating that is present outside theliner is given by T-T1. Therefore, T2, the thickness of the polymericlatex coating, is generally in the range 0.75 to 1.25 of the thicknessof the knitted liner T1. When the ratio is 0.75, the polymeric latexcoating penetrates three quarters of the way into the liner when the topof the coating is flush with the fibers. The penetration may be smaller,but still greater than half way results in polymeric latex coatingextending above the top of the fibers. At the ratio of 1.25, a polymericlatex coating penetrating three quarter way still has half the thicknessof the polymeric latex coating outside the knitted liner. In this range,the geometry of FIG. 1 is accomplished with the polymeric latex coatingcovering the knitted liner, but not penetrating the entire thickness ofthe knitted liner.

A comparison is provided in Table I of typical properties as measuredfor an Ansell 11-800 glove with a 15-gauge knitted liner with a latexcoating produced from an aqueous polymeric latex Ansell 11-600 with a15-gauge knitted liner fully penetrated by solvent-based polyurethanecoating, a Showa product BO-500 with a 15-gauge liner fully penetratedwith solvent-based polyurethane. An exemplary glove according thepresent invention, referred to as Example I, was prepared using an18-gauge knitted liner partially penetrated with carboxylatedacrylonitrile-butadiene latex and is also shown in Table I. Theseexamples were chosen since they directly compare a 15-gauge needleconventional product with an 18-gauge product that is manufactured bymethodology of the present invention. The Ansell 11-800 glove typicallyhas a thickness of 1.15 to 1.5 mm while the thickness of a gloveaccording to the present invention is 0.60 mm to 1.14 mm. In a detailedembodiment, the glove has a thickness of approximately 0.70 toapproximately 0.90 mm. Accordingly the glove according to Example I ismore flexible and provides better tactile sensitivity. The exemplarysize 8 glove of Example I weighs 14.8 grams on average, while a similarsize 8, 11-800 glove weighs 19.2 to 20.7 grams. Table I also shows theeffectiveness of aqueous fluorochemical (FC) coating on the oilpermeability on the product of Example I.

TABLE I Knitting Palm wt Clark Dry Water Oil Oil Needle Thickness oz/sq.Stiffness grip grip grip permeability Product Gauge mm yard cm oz oz ozsec Ansell 15 1.17 14 5.25 108 38 32 1–2 11-800 Ansell 15 0.89 10 7.75100 NA 26 23 11-600 BO-500 15 0.86 7 NA NA NA NA NA Example I 18 0.84 104.2  103 53 38 5 without FC >28,800 with FC

A higher Clark stiffness number corresponds to a higher stiffness glove.The polyurethane coated Ansell 11-600 glove is rather stiff with a Clarkstiffness of 7.75 cm in spite of its reduced thickness sincepolyurethane penetrates the entire thickness of the 15-gauge knittedliner reinforcing the liner creating a higher elastic modulus ‘E’,thereby decreasing deflection and flexibility. The 11-800 glove has aClark stiffness of 5.25 cm, while the glove according to Example I has aClark stiffness of 4.2 cm. A glove according to Example I was treatedwith a fluorochemical (FC) dispersion coating. The oil permeabilities ofthis treated glove and an untreated glove of Example I were measured.The glove with the FC treatment showed improvement in the oilimpermeability as shown in Table I. The gloves of embodiments of thepresent invention have excellent dry grip, water grip and oil grip.

The manufacturing process for the lightweight thin flexible polymercoated glove involves several steps. In a detailed embodiment, an18-gauge knitted liner with nominally 140 denier nylon 66 yarn isdressed on a hand shaped ceramic or metallic former and is immersed in a2-15 wt % calcium nitrate aqueous solution. The calcium nitratecoagulant solution penetrates the entire thickness of the knitted liner.When this coagulant coated liner contacts aqueous polymeric latexemulsion, it destabilizes the emulsion and gels the latex. The coagulantcoated knitted liner dressed on the former is next dipped in the aqueouspolymeric latex emulsion. The polymeric aqueous latex has a viscosity inthe range of 250-5000 centipoise and has commonly used stabilizersincluding but not limited to potassium hydroxide, ammonia, sulfonatesand others. The latex may contain other commonly used ingredients suchas surfactants, anti-microbial agents, fillers/additives and the like.Due to the smaller diameter of the yarn, the distance between the fibersdecrease rapidly forming a pinch region in the knitted liner and whenthe polymeric latex emulsion enters this region, the gelling actionessentially chokes the ingress of the polymeric latex emulsion, therebysubstantially preventing the entire penetration of the polymeric latexemulsion into the thickness of the knitted liner. This penetration andgelling action is sensitive to the viscosity of the polymeric latexemulsion and the depth to which the former with the coagulant coatedliner is depressed into the polymeric latex emulsion tank. The higherthe hydrostatic pressure, the polymeric latex emulsion penetrates moreinto the knitted liner. When the immersion depth is small and theviscosity of the polymeric latex emulsion is high the polymeric latexcoating minimally penetrates the knitted liner resulting in pooradhesion of the coating. Therefore two controllable process variablesare available for precisely and reliably controlling the penetration ofthe polymeric latex coating into the knitted liner, even when theknitted liner is relatively thin. These process variables are 1) thecontrol of polymeric latex emulsion viscosity and 2) depth of immersionof the knitted liner dressed former. Typical depth of immersion neededto achieve this aqueous polymeric latex emulsion to a depth greater thanhalf the thickness of the knitted liner to a penetration that is lessthan the entire thickness is 0.2 to 5 cm, based on the viscosity of thelatex emulsion. Since a latex coating of the glove is generally providedon the palm and finger areas of the glove, the former is articulatedusing a complex mechanism that moves the form in and out of the latexemulsion, immersing various portions of the knitted liner dressed on theformer to progressively varying depths. As a result, some portions ofthe glove may have some degree of latex penetration, however, more than75% of the knitted liner is penetrated at least half way or more thanhalfway without showing latex stain on the skin-contacting surface ofthe glove. The first embodiment of the process produces a thincontinuous latex gelled layer on a thin knitted liner is washed firstand is subsequently heated to vulcanize the latex composition and iswashed to remove coagulant salts and other processing chemicals used tostabilize and control viscosity and wetting characteristics of the latexemulsion. The glove thus produced is better than 30% less in weight andthickness compared to a 15-gauge glove, and has better than three timesthe flexibility.

In a second embodiment of the invention, the polymeric latex emulsionused is foamed. The air content is typically in the 5 to 50% range on avolume basis. The polymeric latex emulsion may contain additionalsurfactants such as TWEEN 20 to stabilize the latex foam. Once the latexis foamed with the right air content and the viscosity is adjusted,refinement of the foam is undertaken by using the right whippingimpeller stirrer driven at an optimal speed first and the air bubblesize is refined using a different impeller run at a reduced speed. Thisfoamed polymeric latex emulsion generally has a higher viscosity andtherefore is more difficult to penetrate the interstices between theyarns in the knitted liner and may require a higher depth of immersionof the former with dressed knitted liner. The penetrated foamed latexemulsion instantly gels due to the action of the coagulant resident ofthe surfaces of the yarns forming chocking regions between the fiberspreventing further entry of the foamed latex emulsion into the thicknessof the knitted liner. The air cells reduce the modulus of elasticity ofthe polymeric latex coating increasing the flexibility of the glove. Theair content in the range of 5-15 volumetric percentile results in foamsthat have closed cells and the polymeric latex coating is liquidimpervious. This coating has a spongy soft feel. Some of the air cellsadjacent to the external surface open out providing increased roughnessand have the ability to remove boundary layer of oil and water from agripping surface, providing increased grip. When the volumetric aircontent is in the range of 15-50%, the air cells are adjacent to eachother and during vulcanization heating step, they expand, touch eachother creating an open celled foam. The polymeric latex coating of theglove is breathable and the glove does not become clammy. If a drop ofliquid is placed on a glove in the palm portion, the liquid maypenetrate the polymeric latex coating especially when the glove is worndue to the stretching of the open air cells. This liquid penetration canbe minimized or prevented depending on the size of the openings in theair cell by applying an aqueous fluorochemical dispersion coating. Thedispersion generally consists of fluorochemical composition dispersed inan aqueous solvent medium to form a coating that is typically 0.5 to 2micron in thickness. The aqueous fluorochemical dispersion coating mayalso be applied to portions of the knitted liner that is not covered bythe polymeric latex coating. The fluorochemical coating may be appliedto the gelled latex prior to vulcanization and the coating curestogether with the latex polymer. The fluorochemical coating may beequally well applied to unfoamed latex coating to prevent oil or waterpenetration through occasional imperfections in the latex coating of theglove.

FIG. 2 illustrates a yarn that can be used in the liner in accordancewith an aspect of the present invention. In one embodiment of thepresent invention, the yarn is a combination of yarns. The combinationof yarns can have a denier of approximately 140 to 150. The processillustrated is a standard technique, but the yarn produced is suitablefor knitting with an 18-gauge needle and produces a lightweight, smallerthickness knitted liner suited for glove production according to thepresent invention. Any yarn or combination of yarns can be used in thevarious aspects of the present invention.

FIG. 3 is a scaled photograph of a prior art liner made using a knittingmachine having a 15-gauge needle. The lighter areas in the photographrepresent the yarn and the dark areas represent spaces between theyarns. The yarn fibers are large in diameter and the space between theyarns is also correspondingly larger. Similarly, FIG. 4 is a scaledphotograph of a liner of an aspect of the present invention made using aknitting machine having an 18-gauge needle, with the lighter areasrepresenting yarn and the darkened areas representing space between theyarn. The 18-gauge yarn that is 140 denier is much smaller in diameterand the knitting process produces smaller space between the yarns. Thesephotographs illustrate that the spacing between the yarns isapproximately one time the diameter of the yarn both with 15-gaugeneedle or 18-gauge needle, however, the present invention uses 221 orsmaller denier yarns to produce a light weight more flexible thinnergloves.

FIG. 5 illustrates an SEM micrograph of a latex glove at 50X showing itscross-section and a portion of angled view of the upper surface of theglove when the latex layer is provided with cavities. The figure alsoshows the glove in full magnification wherein the latex surface at thefinger and palm portions are provided with a plurality of cavities. Themicrograph of a reference marker showing 1 mm distance with 10 dots eachseparated by 0.1 mm. A scale is drawn directly at the 1 mm marker torepresent 5 dots or 0.5 mm. Using this scale each of the cavities thatare cross sectioned are measured and their dimension is shown directlybelow each of the cavities. The cavities are shown to be 300 μm, 225 μm,260 μm, 360 μm, 250 μm, 290 μm, 300 μm and 350 μm. The cavities arenearly uniformly distributed with a mean cavity size of 292 μm. Thestandard deviation of this size is 47 μm, which reflects a small samplesize. The knitted liner of the glove extends below the bottom portion ofthe micrograph and the grey colored latex penetrates more than half waybut does not penetrate all the way into the liner. The cross section ofthe latex layer shows half-moon shaped cross-section of the cavities atthe cut edge. The portion of the upper surface beyond this portionrepresents a shallow angled view of the upper surface and shows nearlyuniform distribution of the cavities in the gripping surface of thelatex glove.

Having thus described various aspects of the invention in rather fulldetail, it will be understood that such detail need not be strictlyadhered to, but that additional changes and modifications may suggestthemselves to one skilled in the art, all falling within the scope ofthe invention as defined by the subjoined claims.

1. A glove, comprising: a knitted liner having a plurality of stitches made from a yarn having a denier 221 or less; and a polymeric latex coating adhered to the knitted liner; the polymeric latex coating penetrating half way or more through a thickness of the knitted liner, and for at least a portion of the knitted liner, the polymeric latex coating does not penetrate the entire thickness of the knitted liner; and the polymeric latex coating having a thickness in a range of 0.75 to 1.25 times the thickness of the knitted liner.
 2. The glove of claim 1, wherein a skin-contacting surface of the knitted liner is substantially free of the polymeric latex coating.
 3. The glove of claim 2, wherein the skin-contacting surface of the knitted liner is approximately 75% or more free of the polymeric latex coating.
 4. The glove of claim 1, wherein a spacing between the stitches is from approximately one to approximately three times the diameter of the yarn.
 5. The glove of claim 1 wherein the yarn has a denier in a range from approximately 70 to approximately
 221. 6. The glove of claim 1 wherein the polymeric latex coating has a plurality of cavities.
 7. The glove of claim 6 wherein the plurality of cavities are uniformly distributed.
 8. The glove of claim 6 wherein the plurality of cavities range have a size from approximately 225 μm to approximately 350 μm.
 9. The glove of claim 1, wherein the stitches are formed by an 18-gauge needle.
 10. The glove of claim 1, wherein the glove has a thickness in a range of from approximately 0.60 to approximately 1.14 mm.
 11. The glove of claim 10, wherein the thickness is from approximately 0.70 to approximately 0.90 mm.
 12. The glove of claim 1, wherein the glove is lightweight.
 13. The glove of claim 1, wherein the glove is flexible.
 14. The glove of claim 13, wherein the glove has a Clark stiffness number of less than approximately 5 cm.
 15. The glove of claim 1, wherein the polymeric latex coating is selected from the group consisting of natural rubber, synthetic polyisoprene, styrene-butadiene, carboxylated or non-carboxylated acrylonitrile-butadiene, polychloroprene, polyacrylic, butyl rubber, a water-based polyester-based polyurethane, a water-based polyether-based polyurethane, or combinations thereof.
 16. The glove of claim 15, wherein the polymeric latex coating comprises carboxylated acrylonitrile-butadiene.
 17. The glove of claim 1, wherein the yarn comprises nylon
 66. 18. The glove of claim 1, wherein the polymeric latex coating is foamed.
 19. The glove of claim 18, wherein the polymeric latex coating has an air content in the range 5% to 50% on a volume basis.
 20. The glove of claim 19, wherein the polymeric latex coating is a closed cell foam with an air content in the range 5% to 15% on a volume basis.
 21. The glove of claim 18, wherein the polymeric latex coating is an open cell foam with an air content in the range 15% to 50% on a volume basis.
 22. The glove of claim 1, wherein the polymeric latex coating is coated with an aqueous fluorochemical dispersion coating on the surface distal from the knitted liner adherent surface.
 23. The glove of claim 22 wherein the latex coating is unfoamed and the fluorochemical dispersion is applied to the unfoamed latex coating.
 24. The glove of claim 22 wherein the latex coating is foamed and the fluorochemical dispersion is applied to the foamed latex coating.
 25. The glove of claim 22, wherein the coating of aqueous fluorochemical dispersion has a thickness in a range of from approximately 0.5 to approximately 2 micron.
 26. A process for making a lightweight flexible glove, comprising: a) creating a glove shaped knitted liner knitted with the spacing between yarns being one to three times the diameter of the yarn, the yarn having a denier of approximately 221 or less; b) placing the knitted liner on a hand shaped ceramic or metallic former; c) dipping the former and the knitted liner in a coagulant solution; d) withdrawing the former and the coagulant coated knitted liner; e) dipping the former and the coagulant coated liner into a tank containing an aqueous polymeric latex emulsion so that the polymeric latex emulsion penetrates half way or more through a thickness of the knitted liner and for at least a portion of the knitter liner, the polymeric latex emulsion not penetrating the entire thickness of the knitted liner; f) gelling the polymeric latex emulsion on a surface of the coagulant coated knitted liner and at interstices between yarns of the knitted liner, creating blockage to prevent further penetration of polymeric latex emulsion; g) withdrawing the former and the knitted liner coated with gelled polymer latex coating; and h) heating the former and the knitted liner coated with gelled polymer latex coating to a temperature to vulcanize the latex coating to form a cured glove with knitted liner adhered to polymer latex cured coating.
 27. The process of claim 26, further comprising i) washing the cured glove.
 28. The process of claim 26, wherein the step of creating the glove-shaped knitted liner includes using a knitting machine with an 18-gauge needle.
 29. The process of claim 26, wherein the coagulant solution is a 2-10 wt % calcium nitrate coagulant solution.
 30. The process of claim 26, wherein the aqueous polymeric latex emulsion is stabilized by potassium hydroxide, ammonia or sulfonates.
 31. The process of claim 26, wherein the aqueous polymeric latex emulsion has a viscosity in the range of 250-5000 centipoise.
 32. The process of claim 26, wherein the dipping depth of the former and the coagulant coated liner into a tank containing the aqueous polymeric latex emulsion is in a range of from approximately 0.2 cm to approximately 5 cm.
 33. The process of claim 26, further comprising foaming the aqueous polymeric latex emulsion to produce a foamed polymer latex coating.
 34. The process of claim 26, wherein the polymeric latex coating is unfoamed, and further comprising coating an aqueous fluorochemical dispersion coating onto the unfoamed gelled polymeric latex coating.
 35. The process of claim 33, further comprising coating an aqueous fluorochemical dispersion coating onto the foamed polymeric latex coating.
 36. The process of claim 26, wherein an aqueous fluorochemical composition is applied to the gelled polymeric latex prior to vulcanization.
 37. The process of claim 34, wherein the aqueous fluorochemical composition is applied to the gelled foamed polymeric latex prior to vulcanization.
 38. The process of claim 26, further comprising applying a coating of a blocking material to the knitted liner to block interstices between yarns of the knitted liner prior to the step of dipping the former and the knitted liner in a coagulant solution.
 39. The process of claim 38, wherein the blocking agent is selected from a group consisting PVA, wax, and solvent-based polyurethane.
 40. The process of claim 26, wherein the latex layer gelled after step f) is dipped in an aqueous latex emulsion to form a second latex layer and is subjected to fluidized salt bath treatment to create cavities and gel the second layer, which is washed to remove salt, creating the cavities in the second layer of latex. 